First, the title of your post says TSS 9s vs 9x7s; the body of your post says TSS 7s vs 9x7s. Which is it? Unless you live in a state where straight 9s are not legal, you will be much better served with straight 9s vs straight 7s or 9x7s. TSS 7s are just not an appropriate shot size for turkeys - huge surplus in energy and penetration ability at the expense of a lot of pattern density. Straight 9s will kill much further than you should shoot. But if you cannot shoot straight 9s, I would prefer 9x7s to straight 7s all day every day.
While, I do not shoot a Cynergy, I have shot a 12 ga Beretta O/U since 2009. If you really only plan to use your open barrel out to 20 yards, I would be shooting cylinder choke and a quality trap load of lead 7.5s to give you the widest possible spread. For the "long" barrel, any turkey choke is going to give you very tight patterns at 20 yds. I would try your factory full, and it is still going to be very snug at 20.
I would suggest moving your crossover point out to 30 yds. Now you are looking at full choke with lead 7.5s or 6s for the open barrel (or mod if you choose to shoot TSS, but TSS is in no way required at 30 yrds from a 12 ga) and a proper turkey choke with TSS for shots over 30.
I personally use 40 yds as my crossover point, use a 1&1/4 oz handload of TSS 9s and a light mod in the open barrel. It has a very forgiving pattern at 20 but will still kill to 40 (110/10"). I use a Sumtoy .675 in the long barrel with a 1&5/8 oz load of TSS 9s. It is tight at 40 (345/10") and will reach out if necessary.
Good luck!
